servercfg: Add always-disabled AutoGCConfig to get doltgresql compiling.

[reltuk]

Goes with dolthub/dolt#8849, which adds a config stanza like:

behavior:
  auto_gc_behavior:
    enable: true

for now, this just gets doltgresql compiling and always disables auto_gc.

[github-actions]

	Main	PR
covering_index_scan_postgres	359.80/s	${\color{red}DNF}$
index_join_postgres	152.16/s	${\color{red}DNF}$
index_join_scan_postgres	183.81/s	${\color{red}DNF}$
index_scan_postgres	12.31/s	${\color{red}DNF}$
oltp_point_select	2719.25/s	${\color{red}DNF}$
oltp_read_only	1865.80/s	${\color{red}DNF}$
select_random_points	110.92/s	${\color{red}DNF}$
select_random_ranges	128.79/s	${\color{red}DNF}$
table_scan_postgres	10.95/s	${\color{red}DNF}$
types_table_scan_postgres	5.55/s	${\color{red}DNF}$

[github-actions]

	Main	PR
Total	42090	42090
Successful	15654	15657
Failures	26436	26433
Partial Successes1	5212	5213

	Main	PR
Successful	37.1917%	37.1989%
Failures	62.8083%	62.8011%

${\color{lightgreen}Progressions (3)}$

domain

QUERY: select '{1,2,3}'::dia;

with

QUERY: SELECT count(*) FROM (
    WITH RECURSIVE t(n) AS (
        SELECT 1 UNION ALL SELECT n + 1 FROM t WHERE n < 500
    )
    SELECT * FROM t) AS t WHERE n < (
        SELECT count(*) FROM (
            WITH RECURSIVE t(n) AS (
                   SELECT 1 UNION ALL SELECT n + 1 FROM t WHERE n < 100
                )
            SELECT * FROM t WHERE n < 50000
         ) AS t WHERE n < 100);

QUERY: WITH RECURSIVE
   x(id) AS
     (VALUES (1) UNION ALL SELECT id+1 FROM x WHERE id < 5),
   y(id) AS
     (VALUES (1) UNION ALL SELECT id+1 FROM x WHERE id < 10)
 SELECT y.*, x.* FROM y LEFT JOIN x USING (id);

Footnotes

1. These are tests that we're marking as Successful, however they do not match the expected output in some way. This is due to small differences, such as different wording on the error messages, or the column names being incorrect while the data itself is correct. ↩

[zachmu]

Doltgres changes seem fine